Myeloid-derived suppressor cells in transplantation

Purpose of review Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature cells that are considered as potential therapeutic targets. Indeed, MDSCs have been shown to suppress immune responses to several types of tumor cells and blocking their suppressive activity may adequately enhance immune response against tumor antigens. On the contrary, the activity of MDSCs may be desirable in suppressing unwanted immune responses such as allograft rejection and might be involved as non-T regulatory cells in the induction and maintenance of transplantation tolerance. In addition, recent data reported that MDSC also control innate immune responses suggesting that MDSC might be important players in controlling ischemia reperfusion injury. Recent findings Herein, we focused on the few recent studies questioning the possible role played by MDSCs in solid-organ transplantation as well as in experimental models of graft versus host disease. Summary A growing body of evidence demonstrates that MDSCs are important physiological regulators of innate and adaptive immunity. Now, accumulating studies suggest that this concept can be transposed to the early and late transplantation immunity. Nevertheless, additional studies with mechanistic approaches in animal together with studies in human are required to better define their position and their interactions with immunosuppressive drugs.